GF07.61-P-3020CY ME-SFI Two-Sensor Control, Function

GF07.61-P-3020CY ME-SFI Two-Sensor Control, Function
- up to model year 08


The ME-SFI [ME] control unit (N3/10) determines the lambda mean value from the oxygen sensor signals downstream of TWC. This value is compared with a stored value for optimum exhaust emissions.
If the deviation is too large after taking a number of measurements, a correction value for the lambda regulation is determined.
The correction variable (value for new oxygen sensor upstream of TWC approx. 0) makes it possible to compensate for aging of the oxygen sensors upstream of TWC within certain limits. If the correction value exceeds the prescribed limit value,the oxygen sensor upstream of TWC [KAT] must be replaced.
The correction value is dependent on the performance map and is achieved by the ME-SFI [ME] control unit by adapting the injection time.

If the prescribed limit value is exceeded or the result of the plausibility check of the oxygen sensor signals (upstream or downstream of TWC) is negative, the engine diagnosis indicator lamp (A1e58) lights up in the instrument cluster (A1).

Exceeding a limit value is stored in the fault memory and can be read out and deleted using DAS.

Two sensor control is only enabled when the catalytic convertors have reached their operating temperature and the oxygen sensors downstream TWC are correct.

The effect of the firewall catalytic converters is monitored based on the oxygen sensor signals downstream of TWC.